On January 10, 1573, German astronomer and physician Simon Marius was born.

Simon Marius (born January 10, 1573 in Gonzenhausen, Germany, and died December 26, 1624 in Ansbach) was a German astronomer and physician.

Simon Marius of the Mondus iovialis from 1586 to 1601 attended Marius¡¯ school in Heilsbronn. His genius of mathematics and astronomy had been shown in his school. By his publication of the results of his observations of the comets in 1596 and the astronomy published in 1599, he gained a reputation. In 1601, he was appointed to be a court mathematician of Count of Ansbach. He went to Prague to study the observation techniques of the Valley of Brah. But the Valley died only four months after his arrival. Then he went to the University of Padua in 1605 for medical studies. He was one of the scholars close to Galileo Galilei. In 1604, he observed a comet, and his students published his observation structure. He then returned to Anchorage. As a mathematician

In 1610, he discovered the four major satellites of Jupiter unrelated to Galileo. Galileo accused him of copying his research results. Earlier, Marius¡¯ students had published a manuscript of Galileo using their own name, which is said to have also been involved in the process. Though so later, Marius suggested that the four satellites be named Galileo satellites. Galileo had intended to name the four satellites by the name of the members of the Medici family, but this suggestion was not later adopted. The discovery of the four satellites was a miracle at the time, as they seemed to be a small solar system.

In 1612, he observed the galaxy of the fairy, the nearest outer river galaxy to the galaxy. Marius seemed to have known that Persian astronomer Sophie had described the galaxy around 905, so he did not claim to be its discoverer. But it was only in 1923 that Edward Hubble used a 2.5 meter telescope at the Wilson Mountain Observatory to prove that it was a star system outside the galaxy. Using the naked eye it looked like a small cloud, with little difference from a 5th-grade star.

The International Astronomical Federation named a ring mountain on the moon after him.